When measuring the induction duration, I put the piston at BDC. After that I rotate the crank CCW until it opens. Degs measured may be for example 35*. Then I rotate it CW until it opens from the other side( it is actually the closing side). Degs measured may be 232*.

232*-35*=197* duration. Is a proper method of measuring the induction duration?

I can't get ATDC measurements because the piston gets stuck.